FAA Order 8020.11A, "Aircraft Accident and Incident Notification, Investigation, and Reporting," dated August 2, 1991, defines destroyed aircraft as "aircraft damaged to the extent that it would be impracticable to return the aircraft to an airworthy condition." The following database lists those aircraft determined by the National Transportation Board as being destroyed. This database, updated monthly by the National Transportation Safety Board, can provide you with a list of all "destroyed" helicopters, or just specific models. Try typing the following in the "Enter a word or phrase" block to get a comprehensive list:

aircraft type: helicopter and aircraft damage: destroyed 

Then click on "Begin Search". To narrow the list to a specific make/model, just type the word "destroyed", then look further down the page for a pull-down menu of all the aircraft manufacturers and select a specific make/model.

NTSB Aviation Accident/Incident Database